diff -up comm-release/mozilla/configure.in.subdir-optflags comm-release/mozilla/configure.in
--- comm-release/mozilla/configure.in.subdir-optflags	2013-10-29 02:20:42.000000000 +0100
+++ comm-release/mozilla/configure.in	2013-10-31 13:07:41.015647853 +0100
@@ -6936,7 +6936,7 @@ MOZ_ARG_ENABLE_STRING(optimize,
 [ if test "$enableval" != "no"; then
     MOZ_OPTIMIZE=1
     if test -n "$enableval" -a "$enableval" != "yes"; then
-        MOZ_OPTIMIZE_FLAGS=`echo "$enableval" | sed -e 's|\\\ | |g'`
+        MOZ_OPTIMIZE_FLAGS=`echo "$enableval" | sed -e 's|\\\\\\\ | |g'`
         MOZ_OPTIMIZE=2
     fi
 else